According to Roll Call’s annual survey of Member wealth, Rep. Michael McCaul (R-Texas) is now the richest Member of Congress, with a fortune worth at least $294 million, a vast increase over last year that was apparently the result of large transfers from his in-laws.

The Texas lawmaker topples Sen. John Kerry (D-Mass.) from the No. 1 position, who reported a minimum net worth of $193 million on his most recent financial disclosure report and is now the third richest Member of Congress.

McCaul also leapfrogged Rep. Darrell Issa (R-Calif.), who remains the second richest Member of Congress, with a reported fortune of more than $220 million.

Roll Call reviewed the annual financial disclosure reports of all House and Senate lawmakers to determine the 50 Richest Members of Congress, as it has done each year since 1990. To calculate minimum net worth, Roll Call adds the minimum value of all assets and subtracts the total minimum value of all liabilities.

While the reports detail Members’ assets — bank accounts, stocks and rental properties — as well as liabilities such as mortgages, student loans and credit card debts, the forms are an imperfect measure of individual wealth. Members are not required to disclose a host of other holdings, including their personal homes or federal retirement savings accounts.

The entry price to Congress’ most exclusive club rose to $6 million in calendar year 2010, the period covered by the most recent reports, up from about $5.5 million the previous year.

McCaul has appeared on Roll Call’s list since his election to the House, when his report for the 2004 calendar year showed a minimum net worth of around $12 million.

But his wealth has grown exponentially since then, nearly doubling from 2008 to 2009 and increasing again by nearly 300 percent from 2009 to 2010.

McCaul ranked fifth among last year’s class of richest lawmakers, with a minimum net worth of at least $73.75 million.

The lion’s share of McCaul’s wealth is held by his wife, Linda McCaul, the daughter of Clear Channel Communications CEO and founder Lowry Mays, and his dramatic rise in net worth appears to be the product of generational wealth transfer.

A footnote to McCaul’s newest report notes that “certain assets” owned by his spouse were “acquired via a gift from spouse’s parents.” The accounts were not identified.

On his financial disclosure, McCaul lists a new asset owned by his wife, the Linda McCaul Descendant Trusts, valued at more than $50 million. According to his report, that trust is invested in several other family partnerships.

McCaul likewise added two trusts under the ownership of his dependent children, including one trust valued at $25 million to $50 million and another at $1 million to $5 million.

Another of Linda McCaul’s investment accounts also appears to double in value, moving from a minimum worth of $25 million to a minimum of $50 million.

Because Members are allowed to report the values of their assets in broad categories — such as $1 million to $5 million — it can be difficult to gauge if an investment has increased or decreased significantly or is merely on the cusp of two categories. An investment worth $4.99 million in reality may appear as a $1 million item one year and a $5 million item the next, even though it had relatively little change.

McCaul’s office declined to comment for this article.

Issa, chairman of the Oversight and Government Reform Committee, also saw a significant bump in his minimum net worth in 2010.

The California lawmaker was the richest House lawmaker and second richest Member of Congress on last year’s survey, with a minimum net worth of more than $160 million. He now posts a total of about $220 million.

Among the reasons for his growth spurt in 2010, Issa spread around some assets of DEI LLC, the property management company he created after he sold an electronics business he owned before coming to Congress. Issa moved several properties previously held by DEI into separate limited liability companies.

While DEI was previously valued at “over $50 million,” the highest category available on standard disclosure forms, Issa now values the company at $25 million to $50 million. But the 11 properties previously held by DEI are now valued at a combined minimum value of $38.2 million, increasing Issa’s overall net worth.

Kerry, who has been at or near the top of the 50 Richest list for 15 years, drops from first to third on the annual survey, despite a small uptick in his minimum net worth.

The Massachusetts Senator’s fortune stems largely from his spouse, Teresa Heinz Kerry, widow of the late Sen. John Heinz (R-Pa.), the scion of the ketchup fortune. When Roll Call first published the 50 Richest list in 1990, Heinz was No. 1.

Kerry’s reported minimum net worth increased more than 2 percent in 2010, as his reported liabilities dropped by $5 million.

The Bay State lawmaker’s fortunes are likely significantly higher, however. Kerry listed more than 140 accounts with a value of only “over $1 million,” a category that applies to assets owned solely by a Member’s spouse.